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The features of B16 melanoma progression in male C57BL/6 mice with initially high and low resistance to hypoxia were studied. To assess the resistance to hypoxia, the mice were placed in a low-pressure chamber at a simulated altitude of 10,000 m. One month after testing, B16 melanoma was inoculated to high- and low-resistant animals. In 19 days after melanoma transplantation, the severity of melanoma progression was assessed by morphological and immunofluorescent methods. The expression of vegf-a and hif-1a in the liver of melanomabearing and control mice was evaluated by real-time PCR. Tumor growth progression was more pronounced in low-resistant mice, which was seen from high weight of the primary tumor node, relative necrosis area, proliferation rates (mitotic index and number of Ki-67+ cells), and expression of vegf-a gene in the liver. In high-resistant to hypoxia animals, the number of caspase-3+ cells dying by apoptosis was higher. The data on more rapid melanoma progression in mice with low resistance to hypoxia should be considered during the search of new prognostic markers and methods for therapy of malignant neoplasms. [ABSTRACT FROM AUTHOR]

To study how Andreev reflection (AR) occurs between a superconductor and a three-dimensional topological insulator (TI), we use superconducting Nb tips to perform point-contact AR spectroscopy at 4.2 K on as-grown single crystals of Bi2Se3. Scanning tunneling spectroscopy and scanning tunneling microscopy are also used to characterize the superconducting tip and both the doping level and surface condition of the TI sample. The point-contact measurements show clear spectral signatures of AR, as well as a depression of zero-bias conductance with decreasing junction impedance. The latter observation can be attributed to interfacial Rashba spin-orbit coupling, and the presence of bulk bands at the Fermi level in our samples suggests that bulk states of Bi2Se3 are involved in the observed AR. [ABSTRACT FROM AUTHOR]

By spatially mapping the Doppler effect of an in-plane magnetic field on the quasiparticle tunneling spectrum, we have laterally imaged the vortex lattice in superconducting 2H-NbSe2. Cryomagnetic scanning tunneling spectroscopy was performed at 300 mK on the ab-surface, which was oriented parallel to the field H. Conductance images at zero bias show stripe patterns running along H, with the stripe separation varying as H-0.5. Regions of higher zero-bias conductance show lower gap-edge conductance, consistent with spectral redistribution by a spatially modulated superfluid momentum. Our results are interpreted in terms of the interaction between vortical and screening currents, and demonstrate a general method for probing subsurface vortices. [ABSTRACT FROM AUTHOR]

Abstract: We report cryogenic scanning tunneling spectroscopy measurements on single crystals of superconducting FeSe1−x Te x , at doping levels of x=0.5 and 0.7, with critical temperatures . Atomically resolved topographic images were obtained, showing large-scale density-of-state clustering which appears to have no periodicity and to vary with the doping. Conductance spectra taken at 300mK showed a generally asymmetric V-shaped background, along with a sharp dip structure within . These spectra appeared to vary over length scale, and not correlated with the topography. The overall spectral evolution versus temperature is consistent with the dip structure arising from a superconducting energy gap which closes above T c , and with the spectral background having a non-superconducting origin. The persistence of finite zero-bias conductance down to 300mK, well below T c , indicates the presence of low-energy quasiparticles on parts of the Fermi surface. We discuss our data in light of some other recent spectroscopic measurements of FeSe1−x Te x , and in terms of its characteristic band structure. [Copyright &y& Elsevier]

Special features of mathematical models used to describe time dependencies of technological parameters of gas compressor unit (GCU) are analyzed during pre-emergency operation of GCU; the models are developed on the basis of the method of grouped arguments. Principal feasibility for well-timed identification of GCU being in pre-emergency situation is demonstrated. [ABSTRACT FROM AUTHOR]